Sentiment402 MCP Adapter (stdio)

A thin MCP server that exposes Sentiment402 snapshot endpoints as MCP tools. It calls the public Sentiment402 API over HTTPS and relays x402 payment requirements when the API responds with 402 Payment Required.

This adapter is intentionally stateless and contains no database credentials or admin headers. It is safe to run locally or package as a public MCP tool.

Tool surface

Tool	HTTP endpoint	Description
`get_global_snapshot`	`GET /v1/snapshot/global`	Global market sentiment snapshot
`get_crypto_pulse`	`GET /v1/snapshot/crypto`	Crypto market sentiment pulse
`get_tradfi_pulse`	`GET /v1/snapshot/tradfi`	TradFi market sentiment pulse
`get_asset_view`	`GET /v1/snapshot/asset/:symbol`	Latest pulse for a specific asset

Common inputs

All tools accept the same optional query inputs (and get_asset_view additionally requires a symbol).

format: full or compact_trading
fields: comma-separated allowlist (only meaningful when format=compact_trading)
symbol: required for get_asset_view

Example tool arguments:

{
  "format": "compact_trading",
  "fields": "headline,trend,confidence"
}

x402 payment handling

When the Sentiment402 API responds with 402, the adapter returns a structured PAYMENT_REQUIRED payload. If SENTIMENT402_X402_PRIVATE_KEY is configured, it will attempt an x402 payment automatically using the options returned by the API. If the payment cannot be completed, the PAYMENT_REQUIRED payload is returned.

Example payload (truncated):

{
  "error": "PAYMENT_REQUIRED",
  "x402Version": 1,
  "resource": "https://sentiment-api.kytona.com/v1/snapshot/global",
  "accepts": [
    {
      "scheme": "exact",
      "network": "base",
      "asset": "USDC",
      "amount": "100000",
      "payTo": "0x..."
    }
  ],
  "rawHeader": "..."
}

Caching

A small in-memory cache is used to reduce repeated requests.

Default TTL: 60000 ms
Cache key: {tool}:{path}?{query}
Only 2xx JSON responses are cached
402 responses are never cached

Configuration

Defaults:

API base URL: https://sentiment-api.kytona.com
API version: v1

Environment variables:

SENTIMENT402_API_BASE_URL (optional) — default https://sentiment-api.kytona.com
SENTIMENT402_API_VERSION (optional) — v1 (default v1)
SENTIMENT402_CACHE_TTL_MS (optional) — cache TTL in ms (default 60000)
SENTIMENT402_USER_AGENT (optional) — default sentiment402-mcp/0.1.0
SENTIMENT402_X402_PRIVATE_KEY (optional) — EVM private key for auto-paying x402 requests
SENTIMENT402_X402_MAX_PAYMENT (optional) — max payment in base units (default 100000, i.e. $0.10 USDC)

No API keys are required for the Sentiment402 API. The private key is only needed if you want auto-pay for 402 responses.

Run locally

Build and start:

pnpm install
pnpm build
pnpm start

You can also run directly in dev mode:

pnpm dev

To point at localhost:

SENTIMENT402_API_BASE_URL="http://localhost:8080" pnpm dev

MCP host config example

Example for a stdio MCP host configuration:

{
  "command": "node",
  "args": ["/path/to/sentiment402/mcp/dist/index.js"],
  "env": {
    "SENTIMENT402_API_BASE_URL": "https://sentiment-api.kytona.com",
    "SENTIMENT402_API_VERSION": "v1"
  }
}

Client Setup Instructions

Claude Desktop

Claude Desktop supports MCP servers via stdio configuration.

Config file location:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json
Windows: %APPDATA%\Claude\claude_desktop_config.json

Option 1: Run from GitHub (Recommended)

{
  "mcpServers": {
    "sentiment402": {
      "command": "npx",
      "args": ["-y", "github:kytona/mcp"],
      "env": {
        "SENTIMENT402_API_VERSION": "v1",
        "SENTIMENT402_X402_PRIVATE_KEY": "your_evm_private_key_here"
      }
    }
  }
}

This automatically downloads and runs the latest version from GitHub.

Option 2: Run from Local Clone

Clone and build:

git clone https://github.com/kytona/mcp.git
cd mcp
pnpm install
pnpm build

Configure Claude:

{
  "mcpServers": {
    "sentiment402": {
      "command": "node",
      "args": ["/absolute/path/to/mcp/dist/index.js"],
     "env": {
       "SENTIMENT402_API_VERSION": "v1",
       "SENTIMENT402_X402_PRIVATE_KEY": "your_evm_private_key_here"
     }
    }
  }
}

Restart Claude Desktop and look for the 🔌 icon to see available tools.

Resources:

ChatGPT Desktop

ChatGPT supports MCP via Developer Mode (requires ChatGPT Plus).

Setup Steps

Enable Developer Mode:
- Open ChatGPT → Settings
- Go to Apps & Connectors → Advanced settings
- Enable Developer mode
Add MCP Server (NPX - Recommended):
- In Apps & Connectors, click Create
- Enter:
  - Name: Sentiment402
  - Command: npx
  - Args: -y github:kytona/mcp
  - Environment Variables:
```
SENTIMENT402_API_VERSION=v1
SENTIMENT402_X402_PRIVATE_KEY=your_evm_private_key_here
```
- Check I trust this application
- Click Create
Use in Chat:
- Click the + in the prompt field
- Go to More → Developer mode
- Enable the Sentiment402 connector

Using Local Clone

Clone and build as described above for Claude
In ChatGPT Developer mode, configure:
- Command: node
- Args: /absolute/path/to/mcp/dist/index.js
- Environment Variables: Same as above

Resources:

Running on a Cloud Server

To run the MCP server remotely and connect from Claude/ChatGPT:

1. Deploy to Cloud

# On your cloud server (AWS, DigitalOcean, etc.)
git clone https://github.com/kytona/mcp.git
cd mcp
pnpm install
pnpm build

# Run with PM2 for persistence
npm install -g pm2
pm2 start dist/index.js --name sentiment402-mcp
pm2 save
pm2 startup

2. Expose via ngrok (Development Only)

# Install ngrok: https://ngrok.com/download
ngrok tcp 8000

# Note the forwarding address: tcp://0.tcp.ngrok.io:12345

3. Configure Client

For Claude or ChatGPT, update the command to connect via TCP:

{
  "command": "node",
  "args": ["-e", "const net = require('net'); const client = net.connect({host: '0.tcp.ngrok.io', port: 12345}); process.stdin.pipe(client); client.pipe(process.stdout);"]
}

⚠️ Security Warning: ngrok exposes your server publicly. For production, use:

VPN (Tailscale, WireGuard)
SSH tunneling
Proper authentication middleware

Resources:

Other MCP Clients (Cline, etc.)

For other MCP-compatible clients, use a similar stdio configuration:

{
  "mcpServers": {
    "sentiment402": {
      "command": "npx",
      "args": ["-y", "github:kytona/mcp"],
      "env": {
        "SENTIMENT402_API_VERSION": "v1"
      }
    }
  }
}

Refer to your client's documentation for the exact config file location.

Test script

The repo includes a stdio test runner that calls a tool and prints the response.

pnpm build
pnpm test:mcp

To point at localhost:

SENTIMENT402_API_BASE_URL="http://localhost:8080" pnpm test:mcp

Optional overrides:

SENTIMENT402_MCP_TOOL (default get_global_snapshot)
SENTIMENT402_MCP_TOOL_ARGS (JSON string)
SENTIMENT402_MCP_SERVER_CMD / SENTIMENT402_MCP_SERVER_ARGS to customize the server process

License

MIT. See LICENSE.

Safety notes

The adapter only calls the public HTTPS API and never touches internal databases.
The MCP response body contains only the API response or a PAYMENT_REQUIRED payload.

Sentiment402 MCP Adapter

Sentiment402 MCP Adapter (stdio)

Tool surface

Common inputs

x402 payment handling

Caching

Configuration

Run locally

MCP host config example

Client Setup Instructions

Claude Desktop

Option 1: Run from GitHub (Recommended)

Option 2: Run from Local Clone

ChatGPT Desktop

Setup Steps

Using Local Clone

Running on a Cloud Server

1. Deploy to Cloud

2. Expose via ngrok (Development Only)

3. Configure Client

Other MCP Clients (Cline, etc.)

Test script

License

Safety notes

Reviews